BBCode is a special implementation of HTML. Whether you can actually use BBCode in your posts on the forum is determined by the administrator. In addition, you can disable BBCode on a per post basis via the posting form. BBCode itself is similar in style to HTML: tags are enclosed in square braces [ and ] rather than < and > and it offers greater control over what and how something is displayed. Depending on the template you are using you may find adding BBCode to your posts is made much easier through a clickable interface above the message area on the posting form.

Simple Explanation

BBCode is a type of code that changes appearance of your words, that has been simplified to a few words put inbetween '[ and ]' for your convienience xD